Pathologic myopia or degenerative myopia

This type of myopia is accompanied by degenerative changes in the eye and, if left unchecke, it can, by various retinal and media complications, lead to blindness. This type of myopia is genetically predetermined.

Congenital myopia

Here the child is born with a high minus number. Usually changes in the eye are also present. More often than not, myopia is restricted to one eye and rarely discovered till late. In this type of myopia, early discovery leads to the possibility of having functional vision with proper optical aids.

How is myopia corrected?

Myopia can be corrected by spectacle lenses or by contact lenses. Partial correction or control can also be achieved by drugs or surgery.

(A) Spectacle lenses: Myopia is corrected by using minus or diverging lenses. Usually a full spectacle correction is givn for distance if the myopia is mild or moderate (upto 5 dioptres). Myopia of greater degree is always undercorrected.

Various authorities now also advocate a much lower separate power for reading. This serves in controlling excessive progression of the power of myopia, specially in children.

(B) Contact lenses: These have the advantage of normally maintaining the size of the object when viewed unlike spectacles which cause an apparent decrease in the size of the object.

Contact lenses, in certain selected cases, certainly do seem to have an excellent capacity to control the myopia which otherwise may be progressing at a rapid pace. They do not seem to have much effect on degenerative or congenital myopia but are now recommended by many authorities for simple myopia. To be effective they should be prescribed at an early age and worn regularly.

(C) Drugs for myopia: Certain medicines have been thought to decrease the rate of progress of myopia by reducing the spasm of the ciliary muscle. The results obtained are variable at best, but since most of them are fairly harmless, a trial does seem merited.

(D) Surgery for myopia: An operation designed by the Russian surgeon Federov can be performed to reduce myopia, especially in those whose power is high. This operation is now being performed in many places in India including Bombay to decrease the myopia and flatten the curvature of the eye. Results, though there are many claims, are at best variable since the degree of fall in power cannot be controlled exactly and in a fair percentage of cases, there is a return to the previous power in a year or two. It is still an experimental technique and undoubtedly may prove efficacious after it has been refined sufficiently.